Dental handpiece

ABSTRACT

The dental handpiece disclosed herein has a housing extending along a longitudinal axis. An air turbine rotatable about a transverse axis is disposed within the housing and fed with air through a hollow rod in the housing and rotatable about the longitudinal axis so that an inclined nozzle at the rod end can drive the turbine in either direction. The turbine drives a transverse friction shaft engaging a friction disc on a drive shaft journalled in the housing for rotation about the longitudinal axis. Spent air my exhaust directly to atmosphere or through a hand controlled port or through a port throttled according to drive shaft speed. A externally releasable chuck in the housing is driven by the drive shaft.

United States Patent [1 1 Flatland DENTAL HANDPIECE [76] Inventor: LloydP. Flatland, l5 Quisisana Dr.,

Kentfield, Calif. 94904 [22] Filed: July 14, 1972 [21] Appl. No.:272,075

Primary Examiner-Robert Peshock Attorney-Marcus Lothrop et al.

[ Dec. 4, 1973 5 7 ABSTRACT The dental handpiece disclosed herein has ahousing extending along a longitudinal axis. An air turbine rotatableabout a transverse axis is disposed within the housing and fed with airthrough a hollow rod in the housing and rotatable about the longitudinalaxis so that an inclined nozzle at the rod end can drive the turbine ineither direction. The turbine drives a transverse friction shaftengaging a friction disc on a drive shaft journalled in the housing forrotation about the longitudinal axis. Spent air my exhaust directly toatmosphere or through a hand controlled port or through a port throttledaccording to drive shaft speed. A externally releasable chuck in thehousing is driven by the drive shaft.

11 Claims, 16 Drawing Figures PATENTEDDEB 4 ma SHEET 1 or 4 FlG 1PAIENIEU DEC 4 I975 SHEET '3 BF 4 1 DENTAL HANDPIECE It is particularlyan object of the present invention to provide a dental handpiece inwhich the tool-holding chuck is driven by means of air underauperatmospheric pressure.

Another object of the invention is to provide means for compactlylocating an air turbine within a'dental handpiece.

A further object of the invention is to provide a way of controlling thedirection of operation of a dental chuck and of controlling itsrotational speed in either direction.

Another object of the invention is to provide an air turbine, low speed,high torque, dental straight handpiece having an air inlet in line withthe handpiece.

Another objectof the invention is to provide a simple means for reducingthe relatively high speed of air turbine rotation to a lower speed moresuitable for dental chuck rotation.

An additional object of the invention is to provide a dental handpiecehaving a chuck that is readily released externally of the handpiecehousing.

A further object of the invention is to provide an air turbine handpiecethat is simple, straightforward, well balanced and easily handled.

An additional object of the invention is to provide a dental handpiecethat is reliable, is unlikely to become clogged and operates at arelatively cool temperature.

A further object of the invention is in general to provide asatisfactory, economical and improved dental handpiece.

Other objects together with the foregoing are attained in the embodimentof the invention described in the accompanying description andillustrated in the accompanying drawings, in which:

FIG. 1 is a plan of one preferred form of dental handpiece pursuant tothe invention;

FIG. 2 is a cross-section to an enlarged scale, the plane of sectionbeing'indicated by the line 2-2 of FIG. 1;

FIG. 3 is a cross-sectional view similar to FIG. 2 but taken on a planeat right angles to the plane of FIG. 2;

FIG. 4 is a cross-section somewhat similar to FIG. 3 but showing amodified form of the device;

FIG. 5 is a cross-section on a diametrical plane and to an enlargedscale showing a chuck utilized in the handpiece;

FIG. 6 is a plan of a device shown in FIG. 5;

FIG. 7 is a cross-section, the plane of which is indicated by the line7-7 of FIG. 3;

FIG. 8 is a cross-section of a modifiedform of handpiece;

FIG. 9 is a fragmentary view of a speed control mechanism;

FIG. 10 is a view comparable to FIG. 9; I

FIG. 11 is a cross-section on the line 1 1-11 of FIG.

FIG. 12 is a cross-section on the line 12-12 of FIG.

FIG. 13 shows a modified form of chuck arrangement;

FIG. 14 is a fragmentary plan of the device shown in FIG. 13; 1

FIG. 15 shows a modified form of speed regulator; and I FIG. 16 is afragmentary plan of the device shown in FIG; 15. r

In its preferred form the dental handpiece of the invention includes anouter housing 6 of a suitable and convenient configuration designed tosupport a dental tool 7 at one end. A flexible hose 8 is attached to anipple 9 at the other end of the handpiece and affords a supply ofcompressed air at a pressure above that of the atmosphere. Preferably,the nipple 9 is at one end of a rod 13 provided with a central passage14 having a closed end 16. The rod extends along the longitudinal axis17 of the handpiece and is rotatable about the axis 17 and within a bore18 formed in a plug 19.The rod 13 is held axially within the plug 19 bya screw 21 threaded into the plug and extending into a semicircularcross channel 22 in the rod so that the rod can be rotated readilythrough at least a half rotation. Air leakage between the rod and theplug 19 is precluded by a pair of 0 rings 23 and 24. The rod at itsinner extremity near the closed end is provided with an angular nozzle26 disposed to intersect the passage 14 and to diverge from the axis 17in one direction when the rod is in one rotated position but, as shownby the dotted lines in FIG. 2, to diverge in the opposite direction whenthe rod is rotated through about a half turn.

The plug 19 is conveniently threaded into the housing 6 and when it isin a selected axial position is clamped or held by a tapered screw 27(FIG. 3). The screw can be driven into an expansion slot 28 in the plugso that a tight expansive frictional engagement can be maintainedbetween the plug and the housing.

Air from the hose 8 which travels through the passage 14 in the rodescapes from the nozzle 26 and impinges upon a turbine wheel 31 having acentral hub 32 and a number of blades 33 preferably inclined withrespect to the cross axis 34 of the turbine wheel. The turbine wheelruns on a cross shaft 36 rotatable about the axis 34 and carried inantifriction bearings 37 and 38 supported in wings 39 and 41 projectingfrom the plug 19. Conveniently, the plug has an arcuate cut-away 42 sothat the turbine wheel vanes or blades pass close to the nozzle in alocation to be impinged upon by the re leased high pressure air. Theturbine wheel turns in one direction when the nozzle is pointed in oneway and the other direction when the nozzle is oppositely pointed.

The turbine shaft 36 is extended by a drive shaft 46 of tapered form.Frictionally engaging the tapered drive shaft 46 is a driven cup 47mounted on a driven shaft 48 coaxial with the longitudinal axis of thehandpiece. A friction material 49 overlies the cup margin so the cup isreadily driven by the shaft 46. The speed of rotation of the turbine isreduced substantially to the speed of rotation of the cup 47. Thefriction between the shaft 46 and and the cup is adjustable by turningthe plug in the housing. The cup and shaft 48 are readily supported in apair of ball bearings 50 and 51 of the usual design. Particularly, theouter race 52 of the bearing 51 is secured in the housing 6 while theinner race 53 of the bearing carries the shaft 48.

Particularly in accordance with the invention, the bearing 51 isutilized to afford a further reduction in speed of the drivingmechanism. In a tubular portion 54 I of the handpiece casing 6 ismounted a ball bearing 56 supporting a final shaft 57. This shaftcarries a hub 58 ending in a castellated or spider portion 59 includingfingers 61 (FIG. 7) arranged to be interspersed be tween the balls inthe bearing 51. Since the inner driving race 53 operates at the speed ofthe shaft 48 and since the outer race 52 is stationary in the housing 6,

the balls partake of an intermediate speed. This is transmitted bycontact of the balls with the interspersed spider fingers 61 so that theshaft 57 operates at consid erably less rotational speed than does theshaft 48. In effect, there are two speed reductions from the turbine 36,one through the friction drive members 46 and 49 and the other throughthe bearing-spider arrangement 51 and 61.

The shaft 57 is connected to the dental tool 7 in any convenient way sothat when air is supplied to the unit, the operator can arrange for thetool to be driven in either of two directions merely by rotating the rod13 from one extreme position to the other so that the nozzle 26 ischanged from one direction to the other. There is a speed reductionthrough the friction mechanism and another one through the bearingmechanism so that the operator can derive a high torque, relatively lowspeed operation of the tool 7 by means of a relatively high speedreversible air turbine 36.

In some instances the two speed reductions are not needed since it maybe desired to have the dental tool 7 operate at a considerably higherrate, a rate more nearly comparable to that of the turbine. In thatinstance, as shown in FIG. 4, the friction cup 47, while otherwise aspreviously described, instead of being mounted on a driven shaft 48 israther mounted on a final shaft 66 carried in bearings 67 and 68 in thehousing 69. The shaft 66, if desired, may even carry an air bushing 71through which some air from the turbine is permitted to escape so thatthe shaft 66 is supported by an air bearing very close to the tool 7 inan accurate fashion suitable for high speed operation.

It is convenient to have a quick acting chuck to hold the tool 7. Aspecial chuck can well be adapted to the arrangements shown in thepreceding figures, particularly as illustrated in FIGS. and 6. In thisinstance the outer jacket 72 suitably supports a final shaft 73 in anyappropriate fashion for rotation about the longitudinal axis of theimplement. The end of the shaft 73 is counterbored to provide an endchamber 74. At its outermost end the chamber holds a plug 76 having acentral passage to receive the shank of the tool 7 and having a threadedengagement 77 with the shaft 73. The plug has a conical inner end 78against which a collett 79 is pressed by a spring 81 seated in thebottom of the chamber 74. The collett is hollow inside to receive thetool 7 and has lateral slots 82 so that when the conical end 83 of thecollett is urged against the conical end of the plug 76 by the spring81, the walls of the slots are narrowed and the collett grips the tool7.

In order that the tool may be released upon occasion, the collett 79supports a cross rod 84 slidable in slots 85 cut in the sides of theshaft 73. A loose collar 86 surrounds the shaft and lies against thecross rod 84 and also lies against an eccentric 87 supported on a shaft88 journalled in the housing 72. A lever 89 is fast on the shaft 88 atone end and conforms generally with the configuration of the casing 72which has an area 90 cut away so that the envelopes of the lever and ofthe easing are substantially continuous. A detent 91 at one end of thelever fits into a dimple 92 in the casing so that the lever normally iscentralized. When the lever is swung to either side of central position,however, it rotates the shaft 88 as well as the eccentric 87 which thenurges the loose collar 86 against the cross rod 84 and moves the rodrearwardly to compress the spring and permit the otherwise unrestrainedparts of the collett 79 to resume their expanded position and to releasethe tool 7.

The foregoing devices do not have any particular means for varying thespeed of operation of the tool except by varying the incoming airpressure through a means, not shown. Since it is helpful to have avariable speed for the tool 7 under many circumstances, I provide suchan arragement in the form of the invention shown in FIGS. 8 to 12inclusive. In this instance there is an outer casing 101 into which isscrewed a plug 102 having a central bore 103 in which a tube 104 isrotatably fixed. The tube is held in place in the plug by a set screw106 allowing the tube to be rotated a half turn, as before. The tube hasa connector 107 to receive an air hose in the previously describedfashion. Air leakage between the tube and the plug 102 is precluded by 0rings 108 and 109. Within the tube is a central passage 111 for incomingair which is released through a nozzle 112 onto a turbine wheel 113disposed in a chamber 114 within the housing 101.

Air entering the chamber 114 through the nozzle 1 12 after leaving theturbine wheel is in some instances free to escape to theatmospherethrough a bleed passage 116 in the plug 102 and leading to theexterior. Flow is controlled by a collar 117 rotatably mounted on theplug 102. The collar has an air passage 1 18 therein. An 0 ring 119precludes leakage. When the collar is in the position shown in FIG. 8there is free exhaust of the spent air from the turbine but when thecollar is rotated so that the passage 118 is out of registering positionwith the passage 116 there is no air escape. Intermediate positions ofthe collar control speed.

The turbine wheel 113, as before, has a driving shaft 121 in frictionalengagement with a friction ring 122 on a driven cup 123. The cup issupported on a shaft 124 coaxial with the axis of the casing andsupported by a thrust and radial bearing 125 as well as by a radial airbearing 126 and finally by a tail bearing 127 in a removable tip 128screwed into the housing 101.

In order to control the speed at which the shaft 124 is driven there isprovided on the driven cup 123 an end face 131 having radial grooves ofconical configuration. Opposite the face 131 is a plate 132 with anormal surface and supported on a hub 133 slidable on the shaft 124. Thehub 133 carries a bushing 134 slidable in the housing 101. The bushing134 is pierced by a number of passages 135 (FIG. 12). The hub 133 isurged toward the left in FIG. 8 and against the conical surface 131 by aspring 136 interposed between the fixed bearing 125 and the hub 133.Interposed between the plate 132 and the cone 131 are balls 138operating in the radial grooves 139.

When the speed of the shaft 124 is relatively slow, centrifugal forcepermits the balls 138 to remain in their central location but as thespeed increases the balls are centrifugally driven outwardly and, actingagainst the conical surfaces 131, displace the plate 132 to the right inFIG. 8 displacing the bushing 134 and compressing the spring 136.Movement of the bushing 134 in an axial direction toward the right inFIG. 8 causes the edge of the bushing to override a number of radialvent holes 141 opening to the atmosphere. There is free air flow aroundthe turbine wheel and from the chamber 114 out through the passages 135and to the atmosphere through the vent holes 141 when the speed is slow.When the speed increases the outflying balls move the bushing 134 partlyto throttle the outlet passages 141 so that air cannot readily escape.This reduces the amount of air flowing past the turbine and reduces itsspeed. In this fashion the turbine can be made to operate at a governedspeed.

At any time when speed governance is not required the user can rotatethe collar 117 so that it no longer blocks the escape passage 116 butrather opens that passage to the atmosphere. Since flow through thepassage 116 is much easier than through the rest of the rather intricateair path, the governor has little or no further effect.

As shown in FIG. 13 a modified form of chuck arrangement may beemployed. The drive shaft 143 is mounted near one end in a bearing 144supported in the housing 146 and has a counterbore 147. The tool 148extends into the counterbore between one or more pairs of gripping balls149. Each ball is located within a conical opening 151 in a relatedspring finger 152. The finger is actually a part of the shaft 143partially separated from the rest of the shaft by saw cuts 153.

Overlying the shaft 143 is a sleeve 154 having a cone 156 at one end andhaving a flange 157 at the other end. A spring 158 surrounds the shaft143 and is disposed between the flange 157 and a collar 159 fast on theshaft 143. Abutting the flange 157 is an eccentric 161 or cam on a crossshaft 162 bearing in the housing 146 and secured to a lever 163 having adetent 164.

When the lever 163 is swung away from the housing, the eccentric 161 isrotated into a position retracting the sleeve 154 against the spring 158and freeing the balls 149 so a tool 148 can be introduced or withdrawn.When a tool is in place and the lever is put into the position againstthe housing shown in FIG. 13, the eccentric 161 turns away from theflange 157 and the spring advances the sleeve 154 so that the cone 156forces the balls 149 tightly to grip the tool 148 so that it rotateswith the shaft 143.

As a modified way of regulating the speed of the driven shaft, as shownin FIG. 10, there is provided a construction in which the driven cup 123is connected to the driven shaft 124, as before. Balls 138 are speedresponsive and move outwardly as the shaft speed increases. As they moveoutwardly the balls press a plate 166 to the right. A hub 167 on theplate then compresses the spring 136 abutting the bearing 125.

When a maximum selected speed has been attained, the plate 166 has beenmoved axially far enough to engage a friction disc 168 having a bearing169 on the hub 167 but restrained by one or more radial rods 171engaging the housing 146. Each of the rods is impelled by the rotationof the parts to lodge at the end of a related helical slot 172 in thehousing and so holds the disc 168 against turning and in proper brakingposition for the speed selected. If the user desires no braking andprefers to let the turbine run free, he moves the rods to the oppositeend of the slots 172, past a detent 173. This moves the disc 168 to adifferent axial position out of range of the plate 166 and affords nofriction braking.

What is claimed is:

l. A dental handpiece comprising a tubular housing having a longitudinalaxis, a drive shaft, means for supporting said drive shaft in saidhousing for rotation about said axis, a dental chuck, means forconnecting said chuck to said drive shaft, a friction disc mounted onsaid drive shaft for rotation about said axis, an air turbine, means formounting said air turbine in said housing for rotation about atransverse axis normal to said longitudinal axis, a friction shaftconnected to said turbine and engaging said friction disc, and means forsupplying said turbine with air.

2. A device as in claim 1 in which said air supplying means is a rodrotatable in said housing about said longitudinal axis.

3. A device as in claim 2 in which said rod has an air passage thereinterminating adjacent said air turbine in a nozzle extending at an angleto said axis.

4. A device as in claim 1 in which said means for supporting said driveshaft includes a ball bearing having spaced balls and said means forconnecting said chuck to said drive shaft includes a spider havingprongs disposed between said balls.

5. A device as in claim 4 in which said ball bearing has an outer racefixed in said housing and has an inner race fixed on said drive shaft.

6. A device as in claim 1 in which said housing includes a port forexhausting air therefrom, and means for throttling air flow through saidport.

7. A device as in claim 6 in which said port is through said housingnormal to said longitudinal axis and said throttling means is a sleeveslidable along said axis.

8. A device as in claim 6 including an additional port for exhaustingair from said housing, and means for manually opening and closing saidadditional port.

9. A device as in claim 6 including means responsive to the speed ofrotation of said drive shaft for operating said throttling means.

10. A device as in claim 9 in which said speed responsive means includesa cone on said friction disc, a hub slidable on said drive shaft andcarrying said throttling means, a plate on said hub opposite said cone,a spring urging said plate and said cone together and balls between saidcone and said plate.

11. A device as in claim 1 in which said means for connecting said chuckto said drive shaft includes means defining a conical surface adjacentthe end of said drive shaft, said chuck is slidable toward and away fromsaid surface, a cross shaft engaging said chuck is slidable in slots insaid drive shaft, a collar is slidable around said drive shaft, a springurges said cross shaft against said collar, a lever is disposed to swingon the exterior of said housing, and means operated by said leverpositions said collar on said drive shaft.

1. A dental handpiece comprising a tubular housing having a longitudinalaxis, a drive shaft, means for supporting said drive shaft in saidhousing for rotation about said axis, a dental chuck, means forconnecting said chuck to said drive shaft, a friction disc mounted onsaid drive shaft for rotation about said axis, an air turbine, means formounting said air turbine in said housing for rotation about atransverse axis normal to said longitudinal axis, a friction shaftconnected to said turbine and engaging said friction disc, and means forsupplying said turbine with air.
 2. A device as in claim 1 in which saidair supplying means is a rod rotatable in said housing about saidlongitudinal axis.
 3. A device as in claim 2 in which said rod has anair passage therein terminating adjacent said air turbine in a nozzleextending at an angle to said axis.
 4. A device as in claim 1 in whichsaid means for supporting said drive shaft includes a ball bearinghaving spaced balls and said means for connecting said chuck to saiddrive shaft includes a spider having prongs disposed between said balls.5. A device as in claim 4 in which said ball bearing has an outer racefixed in said housing and has an inner race fixed on said drive shaft.6. A device as in claim 1 in which said housing includes a port forexhausting air therefrom, and means for throttling air flow through saidport.
 7. A device as in claim 6 in which said port is through saidhousing normal to said longitudinal axis and said throttling means is asleeve slidable along said axis.
 8. A device as in claim 6 including anadditional port for exhausting air from said housing, and means formanually opening and closing said additional port.
 9. A device as inclaim 6 including means responsive to the speed of rotation of saiddrive shaft for operating said throttling means.
 10. A device as inclaim 9 in which said speed responsive means includes a cone on saidfriction disc, a hub slidable on said drive shaft and carrying saidthrottling means, a plate on said hub opposite said cone, a springurging said plate and said cone together and balls betWeen said cone andsaid plate.
 11. A device as in claim 1 in which said means forconnecting said chuck to said drive shaft includes means defining aconical surface adjacent the end of said drive shaft, said chuck isslidable toward and away from said surface, a cross shaft engaging saidchuck is slidable in slots in said drive shaft, a collar is slidablearound said drive shaft, a spring urges said cross shaft against saidcollar, a lever is disposed to swing on the exterior of said housing,and means operated by said lever positions said collar on said driveshaft.